C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof

C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof

C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof

C08J9/26—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out

C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof

C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum

C08J9/286—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum the liquid phase being a solvent for the monomers but not for the resulting macromolecular composition, i.e. macroporous or macroreticular polymers

C08J2357/00—Characterised by the use of unspecified polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds

Abstract

POROUS POLYMERS ARE PREPARED BY POLYMERIZATION OF A POLYFUNCTIONAL METHYACRYLATE SUCH AS TRIMETHLOLPROPANE TRIMETHYLACRYLATE, EITHER ALONE OR IN CONJUNCTION WITH OTHER COMONOMERS IN THE PRESENCE OF A VARIETY OF PHASE SEPARATING SOLVENTS. THESE POROUS POLYMERS ARE USEFUL AS ADSORBANTS IN BOTH AQUEOUS AN NON-AQUEOUS MEDIA AND, WHEN IONIC FUNCTIONAL GROUPS ARE INCORPORATED INTO THE RESIN STRUCTURE, ARE ALSO USEFUL AS ION EXCHANGE RESINS.

'This invention relates to porous, macroreticular polymers of trimethylolpropane trimethacrylate (which hereinafter may be referred to as TMPTMA), andrelated polyfunctional methacrylates, which are useful as adsorb: ants and/ or as ion exchange resins.

Macroreticular resins or polymers are known to; the art and are typically aromatic in character, forcxample, the styrenedivinylbenzene crosslinked macroreticular resins represent a class of. Well-known and presently commercially available materials. These macroreticular resins contain a significant non-gel porosity in addition to the conventional gel porosity. Methods for preparation of these macroreticular resins are disclosed in copending' patent application 749,526 filed July 18, 1958 (Meitzner et al.) and in corresponding British Pats. 932,125, 932,126and in US. Pats. 3,275,548 and 3,357,158.

Briefly, the disclosures of the'above application and patents teachthat macroreticular resins may be prepared by polymerizing monomers which can cross-link in the presenceof a phase separating or phase extending solvent or'mixture of solvents that is miscible with the monomers,

3,663,467 Patented May 16, 1972 scopic channels "extending through the mass and while these microscopic channels are very small, they are large in comparison with the pores of conventional crosslinked gels. Typically, these macroreticular polymers have a surface areaof at least 5 sq. meters per gram and have pores larger than 15 to 20 A. units. The beads are also usually produced in an over all range of particle size of about 10 to 900 microns.

It has now been discovered that if the porous macroreticular resins or polymers are essentially all aliphatic in character and crosslinked with a polyfunctional methacrylate (containing at least three methacrylate groups) there areproduced sorbent products of superior and improved hydrolytic stability, higher wet density, good hydraulic characteristics and superior adsorbent and/or ion exchange properties. Moreover, the aliphatic .porous macroretic'ular polymers of the present invention are effective adsorbents in both aqueous and nonaqueous media, in contrast to prior art materials. The preferred polyfunctional methacrylate is trimethylolpropanetrimethacrylate or pentaerythritrol tetramethacrylate. However, the trimethacrylate of glycerol, glucose pentamethacrylate, sorbitol hexamethacrylate and the polyfunctional methacrylates of polyhydric alcohols of 3 to 6 carbon atoms in chain length may also be used. These polyfunctional methacrylates must contain at least three methacrylate groups as heretofore noted. Sutro polyols which are commercially available mixtures of essentially straight chain polyhydric alcohols of 3 to 6 carbon atoms may be used as the source of. the polyhydric alcohol.

Surprisingly, it has been found that a high degree of porosity and surface area can be produced by using the polyfunctional methacrylates above noted, whereas the dimethacrylates of the prior art gave virtually no porosity or surface activity. For example, the use of a typical glycol dimethacrylate such as disclosed in Hollis 3,357,158, namly butyleneglycol dimethacrylate when polymerized on a l to 1 weight basis with methyl acrylate in the presenc'e of a toluene solvent gave beads with no porosity and with no measurable surface area or pore diameter. However, another copolymer prepared under the same conditions but using trimethylolpropane trimethacrylate and methyl acrylate on a l to 1 basis gave polymer beads of high porosity and excellent internal structure: these beads had a porosity of 0.395 cc. pores/ cc. beads with an average pore diameter of 359 A. (angstrom units) and a surface but which does not dissolve the polymer. The solvent which is usually present in anamount of from about 0.2 to 20 times the weight of the polymerizing monomers must be nonpolymerizable with the monomers, but hot dissolve the polymer. The size of the pores in the polymer and the porosity are somewhatdependantu'pon the kind of solvent employed, e.g.,-whethe1' anaromatic hydrocarbon such as toluene or ethylbenzene or an aliphatic compound such as heptane or an alcohol such as an isoamyl alcohol, or a mixture of such compounds is employed. The polymerization is usuallycarried outin" aquearea of 59 sq. meters per gram. The crosslinked, porous, macroreticular polymers of the present invention are prepared in the form of rigid, water-insoluble, white or opaque beads with particle sizes in the range of about 10 to 900 micronsln terms of mesh size (US. Standard Screen) it is preferred that the particle size be in the range of about 20 to v60 mesh. The porous, macroreticular polymers of the present invention have a surface area of at least about 5 square meters per gram, with the upper limit ranging as high as 2000 square meters per gram. The preferred surface areais-in the range of 25 to 500 square meters per gram. The porous polymers of the present invention also have pores-with an average pore diameter of at least 15 to 20 angstrom units *(A.).

The polymers of the present invention typically contain at'least 2% of the polyfunctional methacrylate and can contain up to of said polyfunctional methacrylate. Typical aliphatic, non-aromatic, monoethylenically unsaturated monomers which may be copolymerized with the polyf unctional niethacr ylate include, for example,

clohexyl, octyl, 2-ethylhexyl, decyl, dodecyl, hexadecyl and octadecyl esters of these acids, hydro-xyalkyl methacrylates and acrylates such as hydroxyethyl methacrylate and hydroxypropyl methacrylate, also the corresponding neutral or half-acid half-esters of the unsaturated dicarboxylic acids including itaconic, citraconic, aconitic, fumaric, and maleic acids, substituted acrylamides, such as N-monoalkyl, -N,N-dialkyl-, and N-dialky-laminoalkylacrylamides or methacrylamides where the alkyl groups may have from one, to eighteen carbon atoms, such as methyl, ethyl, isopropyl, butyl, hexyl, cyclohexyl, octyl, dodecyl, hexadecyl, and octadecyl, aminoalkyl esters of acrylic or methacrylic acid, such as fi-dimethylaminoethyl, 'B diethylaminoethyl, or G-dimethylaminohexyl acrylates and methacrylates, alkylthioethyl methacrylates and acrylates such as ethylthioethyl methacrylate, vinylpyridines, such as 2- vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, and so on. In the case of copolymers containing ethylthioethyl methacrylate, the products can be oxidized to, if desired, the corresponding sulfoxide or sulfone to produce additional interesting adsorbents. There may also be copolymerized with the polyfunctional methacrylates hereinbefore mentioned a difunctional methacrylate such as ethylene glycol dimethylacrylate or trimethylolpropane dimethacrylate, but the difunctional methacrylatemust, not i be present in an amount more than about 25% by Weight, and preferably not more than 10-15% by weight, based on the weight of the polyfunctional methacrylate.

As heretofore mentioned, it is preferred to use a suspension polymerization technique. The polymerization is carried out at temperatures between about 40 C. and 120 C., and at atmospheric, sub-atmospheric or super-atmospheric pressure, thereby producing polymer beads or granules. A variety of suspending agents may be used to aid in the suspension of the monomer-solvent mixture in an aqueous medium as particles of the desired size; Typical of these materials, a great number of which are known in the art are Water soluble polymeric materials such as poly(vinyl alcohol), hydroxyethyl cellulose, methyl cellulose, starch and modified starches, hydrolyzed ethylenemaleic anhydride polymers, hydrolyzed styrene-maleic anhydride copolymers, acrylamide-sodium acrylate copolymers, polyvinylimidazoline polymers and salts thereof, and the like. Other well-known suspending 'agentsare finely divided solids such as magnesium silicate Wax and finely divided silica sold under the name Cab-O-Sil, finely divided clays and the like. Also sometimes useful are the conventional surface active materials such as octylphenoxypolyethoxyethanol, sodium lauryl sulfate, sodium stearate and others. Suitable catalysts, usually in the range of 0.01% to 3% by weight with reference to the weight of the monomer or monomer mixture, may be used to provide free radical initiation in the polymerization reaction. Examples include benzoyl peroxide, lauroyl per- To assist those skilled in the art to practice the present tion are suggested by way of illustration, parts and percentages being by weight unless otherwise specifically noted.

(la) Equipment.All the procedures are carried out with the same equipment except for variations in flask size. Three-necked, round-bottomed flasks of sizes varying from 500 ml. to twelve liters are employed for the preparation of the macroreticular, porous copolymers in quantities from 100 grams'to 1500 grams. The standard tapered necks are fitted with astainless-steel, two paddled stirrer; a 'refiux'condenser; a nitrogen inlet; and a longstemmed, three inch immersion thermometer to which isattache'd a conductance-sensing head that is connected to a pot lifter via anel'ectronic relayfor automatic temperature control. The pot lifter which carried a heating mantle and an air nozzle for both heating and cooling, respectively, and the electronic components of the automatic temperature controlling system are products of Instruments for Research and Industry, Cheltenham, Pa. The stirring motor for maintaining a constant speed of agitation during droplet formation and polymerization is a con-torque with a n adjustable speed of 0 to 750 r.p.m. nIJIanufactured by Eberbach Corporation, Ann Arbor,

wt. percent of organic phase) methyl isobutyl carbinol (MIBC), and 0.5 gram (1.0% of monomer weight) lauroyl peroxide. In this procedure the molar ratio of methyl acrylate to the trifunctional crosslinker is 3.93 and the" molar ratio of monomer solvent (MIBC) to a copolymer is 1.3435. After introduction of the aqueous oxide, t-butyl hydroperoxide, t-butyl perbenzoate cumene solution, sufiicient concentrated aqueous ammonium hydroxide (several drops) is added to raise the pH to within therange of 8 to 9. After flushing the system with nitrogen, the immiscible mixture is stirred at ambient temperature (about 25 C.) at 145 r.p.m. with as many onofi stirring cycles as necessary to disperse completely all the organic liquid into small droplets (0.2 vto 0.5 mm. diameters) in the aqueous layer. When the system in the absence of agitation no longer forms a separate organic layer distinct from the droplet and water layers, the dispersion is heated in an atmosphere of nitrogen at 65 C. for twenty'hours with the same agitation used to develop the droplets in order to polymerize the liquid monomer into solid spheres. The product, a copolymer of 44.8% TMPTMA, 5.2% trimethylolpropane dimethacrylate (TMPDMA), and 50% .methyl acrylate, is cooled to ambient temperature, washed and dried. The-yield of dried product is 45 grams or %of theory. The copolymers physical properties are tabulated below: 1

The porous copolymers of the present invention'ja're passed no phenol is s'till 'detectedin'the efiluent solution particularly useful as'adsorbents in both aqueous and non; 65 and it is not until thirty-one bed volumes are passed that aqueous systems. For example, the absorption of phenols phenol is present to the extent of 50 p.p.m".-in the effiuent from various media with a representative copolymer-of solution. v i the present invention isgiven below: adsorbents of this invention are also useful (6a) Thirty-seven bed volumes of a 50( )p. p .rn. phcnol in adsg'irbtng iolor b odiesffrom aqueous sugar solutions solution in hexane are passed at 25 C. through a five -ml. as well as decolori'ing other aqueous arid non-aqueous column of a macroreticular, porous copolymer of 92% solutions and"systerns.' A I trimethylolpropane trimethacrylate and 8% trimethylol- (7 )'Synthesis of porous copolymer of 50 weight perpropane dimethacrylate (prepared according to the teachcent diacetone acrylamide (N [Z-(Z-methylkoxopentings of (2a) above) operated at a 0.5 gaL/ftfimimfiow yl)] -acrylamide) and SO-weight percentj trirnethylolprorate. Thirty-one bed volumes of the infiuent'soltltion-are 7.5 pane tri'rnethacrylate, -A dispersion of mo nomer".drop' passed before the concentration of the effiuent solution has lets'in' water is prepared by stirring at two phase system or monomer and water at a suitable r.p.m.. at room temper ature to get the proper head size. The .aqueous phase, which is present in the final dispersion at a weight ratio to organic phase of three to one, is composed .of423 gm. (23.47 moles) of water, 171 gm. (2.93 moles) of sodium chloride, and 3;0."gm. (-.-1.5 '10- moie)-poly(vinylimidazolinium bisulfate) salt (MW of 2X10). The poly- (vinylimidazolinium bisulfate')salt is 'dissolvedby slow addition of the powdered solid to a portion of the water with rapid mixing in a three-necked round-bottomed flask. The remainder of the water and the sodium chloride are introduced with stirring to'givea homogeneous aqueous soltuionl The organic phase is prepared separately by mix-v ing 35.0 gm. (0.2068 mole) diacetone acrylamide, 35.0 gm. (0.1034 mole) of commercial trimethylolpropane trimethacrylate (94 wtI percent trimethylolpropane trimethacrylate and 6 wt. percent trimethylolpropane dimethacrylate), 130.0 gm. (1.27 moles) of methylisobutylcarbinol, and 0.7 gm. (1.756X mole) lauroyl peroxide until homogeneous. The organic solution is poured into the reactor, and the organic droplets are formed in the aqueousmedium by stirring (1.83 r.p.m.). When all the organiephasehas been transformed into droplets with no remaining bulk phase, the system is heated to 65 C. andheld at this temperaturefor 20 hours. The resulting opaque copolymeris cooled to room temperature; freed of motherliquor; washed three times with water (one bed-volume each wash), five. times with methanol, three times withethylene dichloride, four times with methanol; anddried overnight in a steamoven at 75 C. A20 to 30 mesh cut of U.S. v Sieve Series is measured for physical properties. The yield of driedcopolymer is 95.7% of theory. The weight percent nitrogen in the final copolymer measures 3.94%. The physical properties are given below:

Surface area, m? g." -68 Average pore diameter, A.--35l i This copolymer is effective in adsorbing phenol from nonaqueous solutions, and in particular, in removing. phenol from hexane and also phenol frombenzene. A very practical application of this is the removal of phenol from crude oils.

.'(9) Synthesis of porous copolymer of 2-(ethylsulfinyl)- ethyl methacrylate with trimethylolpropane trimethacrylate.-Aqueous hydrogen peroxide (11.3 g., 0.1 mole of 30 wt. percent H 0 37.8 g. (0.10 eq. wt. based on elemental sulfur analysis) of a copolymer of wt. percent ethylthioethyl methacrylate cross-linked with 47 wt. percent..trimethylolpropane trimethacrylate and 3 wt. percent. trimethylolpropane dimethacrylate, and 200 ml. of glacial acetic acid are introduced into a reactor with agitation. A very mild exotherm of about 3 C. occurs upon mixing the three components at ambient temperature. After standing over night ,for approximately sixteen hours, the mixture contains unreacted hydrogen peroxide. The mixture is, therefore, heated at 50 C. for twenty hours after which a test for hydrogen peroxide is negative. The interstitial liquid is siphoned from the copolymer and the copolymer is washed stepwise three times with water and four times with methanol. Each treatment With water and methanol is carried out for a duration of about forty minutes after which the bulk liquid is siphoned off. The yield of dried product is 93.6% of theory; the elementalanalysis indicates 7.60 wt. percent sulfur, 27.97 wt. percent oxygen, 54.29 wt. percent carbon, and 7.51% hydrogen. The physical properties are given below:

Average pore diameter, As-375 This product (oxidized to the sulfone form) shows excellent adsorbent properties, for example in adsorbing benzene from hexane, and in removing by adsorption oleic acid or acetic acid from toluene.

The aqueous to organic phase weight ratio is approximately three to one. The monomer droplets are formed at room temperature by agitation at the stirring speed which provides the proper particle size (153 r.p.m. in this example). The dispersion is heated to 65 C. and kept at 65 C. for twenty hours. The opaque white beads are cooled to ambient temperature; washed three times with water, five times with methanol, three times with ethylene dichloride, and four times with methanol; and dried in a steam oven overnight at 75 C. The yield of dried product is 100 gm. or 100% of theory. A 20 to 30 mesh cut of US. Sieve Series is measured for physical properties, which are given below:

The aqueous to organic phase weight ratio is approximately three to one. The copolymer is obtained from the monomer droplets by polymerization at a stirring speed of 200 p.r.m. at 65 C. for 20 hours. The opaque white beads of copolymer are isolated and cleaned up as described in procedure (7) above. The physical properties a.

of the 20-30 mesh cut (U.S. Sieve Series) are given below. The yield of dried product is 99 gm. or 99% of theory.

(13) Synthesis of porous copolymer of N,N-dimethylacrylamide with pentaerythritol tetramethacrylate.A dispersion of monomer droplets in water is prepared and polymerized as described in procedure (7) above. The

organic phase is composed of 50 gm. (0.5044 mole) N, a

N-dimethylacrylamide, 37.5 gm. (0.0918 mole) pentae-. rythritol tetramethylacrylate, 12.5 gm. (0.0367 mole) pentaerythritol trimethacrylate, 100 gm. (0.9420 mole) xylene, and 1.0 gm. (2.51X10-3 mole) lauroyl peroxide. The monomers of pentaerythritol tetramethacrylate and the trimethacrylate are supplied as a 51 wt. percent solution in xylene, wt. percent of which is the tetra-ester and 25 wt. percent of which is the tri-ester. The droplet size distribution is obtained at 198 r.p.m.; the yield of opaque while copolymer is 88% of theory. The physical properties of the product cleaned up as in procedure (7) above, are given below. The nitrogen content of the copolymer is 6.15 wt. percent.

(14) Synthesis of porous copolymer of 2-(N,N-dimethylamino)ethyl methacrylate crosslinked with pentaeryth ritol tetramethacrylate.-Porous copolymer is spherical bead form is obtained as described in procedure (7) above. The monomer droplets are formed at 176 rpm; the polymerization and product clean-up are'carried out exactly as described in procedure (7). The organic phase is prepared from 50 gm. (0.3180 mole) 2-(N,N-dimethylamino)ethyl methacrylate, 37.5 gm. (0.0918 mole) pentaerythritol tetramethacrylat'e, 12.5 gm. (0.0367 mole) pentaerythritol trimethacrylate, l00'gm. (0.9420 mole) xylene, and 1.0 gm. (2.5l 10- mole) lauroyl peroxide. The monomer of pentaerythritol estern is handled as a 51 wt. percent solution of ester in xylene; the ester composition is 75 wt. percent pentaerythritol tetramethacrylate. The yield of product with 3.32 wt. percent nitrogen is 70 gm. or 70% of theory. The physical properties of the product are given below.

'The porous copolymer products of procedures (11), (12), (13) and (14) are all effective adsorbents and may be used, for example, to remove by adsorption phenol from hexane. I

What I claim is:

1. A porous, adsorbent macroreticular essentially all aliphatic polymer having pores with an average diameter of at least 15 to 20 A. and a surface area of at least 5 square meters per gram, said polymer being rigid and crosslinked and composed of 2 to 100% by weight of a polyfunctional methacrylate containing at least three methacrylate groups.

2. A porous, macroreticular polymer according to claim 1 wherein the polyfunctional methacrylate is trimethylolpropane trimethacrylate or pentaerythritol tetramethacrylate.

3. A porous, macroreticular polymer according to claim 1 wherein the polymer contains an aliphtaic, non-aromatic, co-monomer which may be monoethylenically unsaturated or which may be a difunctional monomer, copolymerized with the polyfunctional methacrylate.

4. A porous, macroreticular polymer according toclaiin 1, in the form of finely divided beads. v

5. A porous, macroreticular polymer according to claim 3 wherein the co-monomer is diacetone acrylamide or N, N-dimethylacrylamide. V

6. A porous, macroreticular polymer according to claim 3 wherein the co-monomer is Z-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylate.

7. A porous, macroreticular polymer according to claim 3 wherein the co-monomer is 2-(N,N-dimethylamino) ethyl methacrylate.

9. A porous, macroreticular polymer according to claim 1, said polymer being composed of about 50% methyl acrylate, about 5.2% trimethylolpropane dimethacrylate and about 44.8% trimethylolpropane trimethacrylate, all percentages being by weight.

10. A porous, macroreticular polymer according to claim 1, said polymer being composed of about 92% trimethylolpropane trimethacrylate and about 8% trimethylolpropane dimethacrylate, all percentages being by weight.

11. A porous, macroreticular polymer according to claim 1, said polymer being composed of about 50% methyl methacrylate, about 46.5% trimethylolpropane trimethacrylate and about 3.5% trimethylolpropane dimethacrylate, all percentages being by weight.

12. A process of preparing a porous, adsorbent, macroreticular essentially all aliphatic polymer having pores with an average diameter of at least 15 to 20 A. and a surface area of at least 5 square meters per gram, said polymer being rigid and crosslinked and composed of 2 to 100% by Weight of a polyfunctional methacrylate containing at least 3 methacrylate groups, which comprises suspension polymerizing said polyfunctional methacrylate at a temperature between about 40 C. to 120 C., and in the References Cited UNITED STATES PATENTS 3,220,960 11/1965 Wichterle 2602.5 M 3,418,262 12/1968 Werotte et a1. 260-25 B 3,275,548 9/1966 Walters 210-24 3,357,158 12/1967 Hollis 2602.5 R 3,531,463 9/1970 Gustafson 260211.5

OTHER REFERENCES Rohm and Hass Company bulletin CM-32 June 1969. Rohm and Hass Company bulletin SP-237 March 1967.